+ datafilter(json) {
+ // find viable rows from json data
+ const selection = new Words(json, this.preset.cat);
+
+ if (this.preset.images) {
+ selection.filter(id => json[id][2]);
+ }
+ if (this.preset.level !== undefined) {
+ selection.filter(id => json[id][1] <= this.preset.level);
+ }
+
+ if (this.preset.distinct) {
+ // remove referenced categories
+ selection.filter(id => !selection.get(id).subs.length);